On a tangential issue, I learned that Halloween is called Dia de las Brujas (Day of the Witches) in Spanish. Based on the Wikipedia, Halloween has only really be celebrated in Mexico since the 1960s:
In Mexico, Halloween has been celebrated since roughly 1960. There, celebrations have been influenced by the American traditions, such as the costuming of children who visit the houses of their neighbourhood in search of candy. Though the "trick-or-treat" motif is used, tricks are not generally played on residents not providing candy. Older crowds of preteens, teenagers and adults will sometimes organize Halloween-themed parties, which might be scheduled on the nearest available weekend. Usually kids stop by at peoples' houses, knock on their door or the ring the bell and say "¡Noche de Brujas , Halloween!" ('Witches' Night—Halloween!').
Halloween in Mexico begins three days of consecutive holidays, as it is followed by All Saints' Day, which also marks the beginning of the two day celebration of the Day of the Dead or the Día de los Muertos. This might account for the initial explanations of the holiday having a traditional Mexican-Catholic slant.